I've got a 14' aluminum with a 25 horse Yamaha (post-divorce boat - pre-divorce was a 28' sportfisher) that I've turned into a fishing machine. Fish everything from Lk Washington cuthroat to Neah Bay Salmon and everything in-between.
I use the $100 hummingbird and have loved it - uncomplicated, waterproof, and it shows me individual fish, bait, bottom, etc. Not to say there aren't advantages to $600 fishfinders but for the money this has been perfect.
Other things I've done to maximize fishing from a small boat is: Turned my middle bench seat into a fish box by installing a 13" by 36" hatch, hatch liner, and drain. Removing a large cooler from the boat sure frees up space. Installed two 13" x 15" hatches/hatch liners in the rear bench seat - one for the battery - the other for a dry box. Once again freeing up premium deck space. Installed a coho cleaner with ss bolts/wingnuts over the side - gotta bleed those fish, clean 'em quick, and get them on ice. Installed a Scotty 1060 downrigger on 1 side. - I run 2 rods off of this - this small of a boat I didn't want to hang two downrigger cables down that close together and then turn sideways in a strong tide flow. This has been working great with far fewer tangles than if I were running two downriggers. In my battery box/hatch I installed a fuse panel and then installed running lights and a 12v outlet for cell/vhf charging. BTW I highly recommend a submersible, handheld vhf tethered to the boat. They can be had for under $150 and are a necesesity.
My sons and I caught 31 salmon and 30+ seabass, ling cod, etc at neah bay from this rig last weekend.
Good luck, be safe, have fun!
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. . . and God said unto them, Be fruitful, and multiply, and have dominion over the fish of the sea . . .